Several variations of header units have been used in combines or harvesting machines for harvesting row crops such as corn and cotton. One of the first such header units was a corn head with fixed spacing between the row units. Several other corn heads allowing variable spacing between the row units were then developed.
With the advent of the variable row width header units, the last several years has seen a rapid increase in the research and development of the effect of varying row widths on the growth of corn and other row crops. The existing corn heads and harvesting machines are designed to efficiently harvest corn planted in rows having a row width of greater than 20 inches, because the existing corn heads have the gatherers of their row units in the same plane, thereby limiting how close the row units can be arranged together.
For example, a typical existing corn head with a plurality of row units has both the gatherers of each row unit positioned in the same plane. Thus, the adjacent gatherers of any two adjacent row units are also positioned in the same plane. This limits how close the adjacent row units can be positioned as the adjacent gatherers of the adjacent row units interfere with each other if the adjacent row units are positioned too close to each other. As the technology to build the chains and gears required for efficient operation limits the minimum width of a row unit, the positioning of adjacent row units determines the minimum crop row width that can be efficiently harvested by the existing corn heads. Thus, current technology limits the row widths to about 20 inches because the gatherers in adjacent row units of the existing corn heads interfere with each other if they are brought any closer.
Recent research on the spacing of the corn rows has indicated special benefits for narrower row spacings that are 12-15 inches apart. In addition to the obvious increase in yield and crop population, these benefits include improved erosion control and better weed control. The narrower rows also require less chemicals and pesticides per unit of yield thereby benefiting the environment.
Existing header units are not designed to harvest rows having a spacing of 15 inches or less. Consequently, they are very wasteful and inefficient in harvesting narrow rows leading to a sub-optimal harvesting efficiency.
The problems identified above are not intended to be exhaustive but are among the many that reduce the effectiveness of current solutions to the problem of harvesting crops planted in narrow rows. Other problems may also exist; however, those presented above should be sufficient to demonstrate that currently known solutions are amenable to worthwhile improvement.